There are many ways to assemble articles. The following uses a keyboard as an example for discussion. The keyboard is a data input device to function as a communication interface between users and a computer system. It consists of many keys that include character keys, direction keys and function keys and the like, for entering different data. The keyboard has many types. Most keyboard shells are assembled with tapping screws engaging apertures. While fastening by the tapping screws, the shells often deform due to torsion force and stress. Deformation is especially severe when the shells are lengthy. Even the gaps between the shells and the tapping screws result in a bad surge-test or a bad high-pressure-test. So fastening the shells by the tapping screws is not a facilitating way.
At present the technique of coupling through an ultrasonic welding process has been adopted in many areas. Reference can be found in U.S. Pat. Nos. 5,475,919 and 6,546,621.
U.S. Pat. No. 6,546,621 entitled “Package structure and method for a card” teaches a technique, which couples a first conductive cover and a second conductive cover with a first plastic frame and a second plastic frame by ultrasonic welding, to form a first half case and a second half case. U.S. Pat. No. 5,475,919 entitled “PCMCIA card manufacturing process” also adopts the ultrasonic welding technique to couple an upper plastic case with a lower plastic case. However, the product coupled by the ultrasonic welding technique has one problem, i.e. when it is disassembled for repairs, the welding structure is destroyed and the plastic cases have to be discarded. This results in wasting of costs.